While interest in nano technology has been increasing since the 1990s, research on nanocomposites has also been actively progressing. Nanocomposite means a composite, in which fillers having a size of 1 to 100 nm such as polymers, inorganic materials and/or metal particles are uniformly dispersed in a polymer matrix.
Nanocomposites have significantly improved or novel characteristics compared to conventional polymer compounds having particles with a size of 1 to 100 μm dispersed therein, owing to very large surface areas (interface areas) of elements contained therein and significantly reduced distances between particles. Since nanocomposites have advantages including greatly improved thermal and mechanical characteristics, high liquid and gas permeability and low flammability even by addition of only a small amount of dispersion particles, as compared to conventional inorganic fillers or reinforcing agents, they have attracted the attention of researchers and companies.
Nano-scale particles (fillers or reinforcing agents) widely used in the manufacture of nanocomposites include a layered silicate (ex. phyllosilicate). The nanocomposite is generally manufactured by preparing an additive with high purity by purifying or synthesizing a layered silicate, pretreating the additive so as to be well dispersed in a polymer resin, and mixing the pretreated additive with the polymer resin.
In the manufacture of the nanocomposite, the most important part is uniform dispersion of the nano-scale additive such as the layered silicate in the resin. In order to achieve the uniform dispersion, various techniques have been suggested.
European Patent No. 1801158 discloses a method of preparing a natural or synthetic clay compound intercalated and/or exfoliated using a block copolymer having a latex form, in which a diblock copolymer of 4-vinylpyridine and styrene is used as the block copolymer. In addition, U.S. Patent Publication No. 2006-74167 discloses a nanocomposite including a layered silicate and a block copolymer compatible with the silicate, in which a diblock copolymer of styrene and 4-vinylpyridine is also used as the block copolymer.
All of the above-mentioned prior techniques use a block copolymer including specific monomers as an exfoliating compatibilizer that is inserted between layers of the silicate. However, the block copolymer is difficult to efficiently prepare because of a very complicated and costly preparation process. Accordingly, the techniques disclosed in these prior documents are difficult to commercialize as they are hardly compatible with actual nanocomposite preparation processes.